The content covers fundamental concepts and principles of object-oriented programming (OOP) across various programming languages such as C++, Java, and C#. Topics include classes, objects, inheritance, encapsulation, polymorphism, and design patterns. The documents also address programming paradigms, software development processes, and best practices for effective code organization and management. Additionally, discussions on specific features like exception handling, operator overloading, and memory management enhance the understanding of OOP's application in software development.